There is liquid chromatography as one of the methods to analyze ingredients in liquid which contains several organic compounds. As the liquid chromatography, high-speed liquid chromatography (HPLC), which uses packing materials of improved particle-size distribution for the separation column, is widely adopted now. The above method uses several detecting means for detecting ingredients in eluate which flows out from the separation column. As a general one, for instance, there is a differential refractometer. Though this can be used all-roundly, it has problems that it lacks selectivity in kinds of substances and it has not so high sensitivity. On the other hand, an ultraviolet absorption detector is most popular among selective detectors; however, it cannot be applied to compounds such as alcohols, which do not show effective ultraviolet absorption. For this reason, the method, which analyzes derivatives being combined with ultraviolet-absorbing groups, is conducted, however, this method is complicated. Also there are a fluorescence detector and a chemical luminescence detector among selective detectors. Though they can detect specific compounds in high sensitivity, the scope of compounds to be detected is more limited.
Furthermore, there is an electrochemical detector as shown in the patent document JP-A-5-296964 (Hei) for the detector to be used in HPLC. This is applied for the analysis of catecholamines and so on, as explained in the above patent document concerning the analysis of physiologically active substances and metabolites of creatures. The above patent document is explaining that its coulometric detector, the active electrode of which uses glassy carbon having small pores of 1 to 100 μm in diameter on its surface, has far higher sensitivity in the electrochemical conversion characteristic than the former detectors using porous graphite.
Patent Document 1: JP-A-5-296964(Hei)